Non-aqueous electrolyte batteries are widely used as the main power source or memory backup power source for various electronic devices. With recent spread of small portable devices such as cellular phones and digital still cameras, there has been ever-growing demand for non-aqueous electrolyte batteries. Moreover, the devices become smaller in size and lighter in weight, and on the other hand, they are required to have more sophisticated functions and tend to have a larger memory capacity. Accordingly, there is a growing demand for the main power source and the backup power source to be small in size and have a high capacity. Under these circumstances, examinations are being made to use a material with high energy density, such as silicon (Si) or tin (Sn), as a battery reaction active material. In particular, silicon, which can be alloyed with lithium until the composition becomes Li4.4Si and has a theoretical capacity of as high as 4199 mAh/g, is regarded as promising for providing a battery having a high capacity.
On the other hand, various studies have been made on the improvement of the charge/discharge cycle characteristics and low-temperature discharge characteristics of non-aqueous electrolyte batteries with higher capacity. For example, silicon becomes active when it absorbs lithium, and is apt to induce a side reaction of the non-aqueous electrolyte. In order to solve this problem, one proposal suggests that an acylated cyclic carboxylic acid ester compound be included in the battery, to inhibit the decomposition reaction of the carbonic acid ester contained in the non-aqueous electrolyte, and thereby to improve the charge/discharge cycle characteristics (Patent Literature 1). Another proposal suggests that fluoroethylene carbonate be contained in a specific ratio in a non-aqueous electrolyte containing a carbonic acid ester, thereby to suppress the swelling of the battery due to decomposition of the non-aqueous electrolyte (Patent Literature 2).